1. Field of the Invention
The present invention generally relates to a wobble damping system for spin-stabilized airborne projectiles and more particularly to an improved passive system.
2. Description of the Prior Art
As will be appreciated by those skilled in the art, a large class of projectiles in free flight through the air rely on spin stabilization to prevent excessive wobble while in flight. Through the use of rifling, upon launch the projectile is spun about its longitudinal axis. Despite spin stabilization, forces on the projectile while in flight will cause the projectile to wobble (i.e., yaw and pitch with respect to the spin axis) and it is desirable to dampen this oscillatory motion quickly.
U.S. Pat. No. 3,034,745 issued to D. J. Stewart discloses a spin axis stabilized space vehicle with a passive spin axis stabilizer comprised of a ring with internal raceways positioned coaxially with the spin axis. A dense fluid partially fills the raceways. Wobble induced sloshing of the fluid in the raceways provides a damping action.
The spin axis stabilizer proposed in the Stewart patent is not altogether satisfactory for many applications. Its ratio of generated damping force to stabilizer weight is low. The center of gravity and axis of the stabilizer changes its axis relative to the spin axis. Further, the stabilizing force generated in response to various wobble conditions is not predictable.